Then along comes Apple with a rare earnings missfollowed by trouble at Zynga and Amazon. Whoa, something is happening here. Fortune 500 companies like Apple, Nike and McDonalds are nothing if not experts when it comes to managing earnings expectations.

Chief executives and chief financial officers will jump through accounting hoops to please Wall Street. Because when it comes to measuring corporate success, the first thing many want to know is: Did you make your numbers?

Investors want stability and predictability. Management, in turn, wants to evoke credibility and maximize share price, while avoiding any possible litigation from earnings surprises. Meeting and beating estimates also just happens to boost managements compensation and stock options. Not that theres anything wrong with that.

With so much at stake, its easy to see why managing quarterly earnings can become the top priority for many corner offices. But clearly the economic problems in Europe and China have upended those efforts of late. The result is a second-quarter earnings season that is shaping up to be one of misses and downward revisions in many key sectors.

United Parcel Service on Tuesday lowered its forecast for 2012 and said its third-quarter earnings will fall below last years results. UPS is a closely watched gauge of the broader economy because it moves millions of packages a day between businesses and consumers.

Economies around the world are showing signs of weakening and our customers are increasingly nervous, chairman and CEO Scott Davis said in a conference call with analysts.

Johnson & Johnson lowered its full-year profit forecast last week after announcing that second-quarter income fell by half due to reduced sales and charges for litigation and other items. The gloomy outlook came as the companys shares are trading near their highest level in more than three years.

Goldman Sachs strategists warned clients earlier this month to expect lower corporate earnings, even with the revisions analysts have been making to reflect the weaker global economy. Investors have responded by moving to more defensive stocks like telecommunications services, consumer staples and health care. The slowing prompted the Federal Reserve to consider further stimulus measures to boost the economy.

The earnings misses indicate how quickly the economy has soured. Many companies have not been able to get in front of the downturn to better manage their faltering profits.

After all, when it comes to meeting or beating consensus earnings estimates, companies are not passive observers. Managers will often use a mix of accounting and economic actions to ensure they make their numbers. The easiest step is to sell stuff to book a capital gain just before the accounting date in order to provide a one-time boost to profits.

Along the way, companies will often guide the market. A 2005 study found 80 percent of chief financial officers guided analysts to manage expectations. Often that guidance is slightly less than what a company expects to really make. Then, amazingly enough, the earnings come in a penny or two above expectations. Everyone goes home happy.

For years, General Electric was a master at beating expectations. Turns out the company did this in part by booking profits on sales that were really loans and through the use of exotic derivatives. The Securities and Exchange Commission alleged in a lawsuit that two sets of transactions were intentionally designed to defraud investors. In 2009, the company paid a $50 million fine to settle the lawsuit with the SEC.

Companies often get punished too harshly for missing their earnings targets. A study by University of Iowa accounting professor Paul Hribar found that firms that narrowly beat their forecast by managing their earnings have a lower stock performance in the following three years than firms that do not manipulate their balance sheets but narrowly miss their estimate.

But its easy to see why companies often do whatever it takes not to disappoint Wall Street. Despite increasing sales, Buffalo Wild Wings missed its earnings the other day. Its shares quickly dropped $9.45, or 12 percent, to $69.45.